package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;
import com.lagou.utils.TokenHandler;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * 查询对象
 */
public class simpleExecutor implements Executor {
    @Override
    //本质执行的还是jdbc代码
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        //1.注册驱动，获取连接
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql语句:select * from user where id=#{id} and username=#{username}
        //转换成：select * from user where id=? and username=?
        //转换过程中对#{}里面的值进行解析存储
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数
        //获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass =  getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0 ; i<parameterMappingList.size() ; i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String context = parameterMapping.getContext();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(context);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);


        }

        //5.执行sql
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);


        ArrayList<Object> objects = new ArrayList<>();

        //6.封装返回结果集
        while (resultSet.next()){
            Object o = resultTypeClass.newInstance();
            //元数据
            ResultSetMetaData metaData = resultSet.getMetaData();
            for(int i = 1;i<=metaData.getColumnCount();i++){
                //字段名
                String columnName = metaData.getColumnName(i);
                //字段的值
                Object value = resultSet.getObject(columnName);

                //使用反射或者内省，根据数据库表和实体的对应关系，完成封装
                //内省库中的类PropertyDescriptor，
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);
            }
            objects.add(o);

        }

        return (List<E>) objects;
    }

    @Override
    public <E> void add(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, Exception {
        //1.注册驱动，获取连接
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql语句:select * from user where id=#{id} and username=#{username}
        //转换成：select * from user where id=? and username=?
        //转换过程中对#{}里面的值进行解析存储
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数
        //获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass =  getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0 ; i<parameterMappingList.size() ; i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String context = parameterMapping.getContext();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(context);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);


        }
        //5.执行sql
        preparedStatement.execute();
    }

    @Override
    public <E> void delete(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, Exception {
        //1.注册驱动，获取连接
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql语句:select * from user where id=#{id} and username=#{username}
        //转换成：select * from user where id=? and username=?
        //转换过程中对#{}里面的值进行解析存储
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数
        //获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass =  getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0 ; i<parameterMappingList.size() ; i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String context = parameterMapping.getContext();
            String toString = context.toString();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(context);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);


        }
        //5.执行sql
        preparedStatement.execute();
    }

    @Override
    public <E> void update(Configuration configuration, MappedStatement mappedStatement, Object... params) throws SQLException, Exception {
        //1.注册驱动，获取连接
        Connection connection = configuration.getDataSource().getConnection();

        //2.获取sql语句:select * from user where id=#{id} and username=#{username}
        //转换成：select * from user where id=? and username=?
        //转换过程中对#{}里面的值进行解析存储
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);

        //3.获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        //4.设置参数
        //获取到了参数的全路径
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterTypeClass =  getClassType(parameterType);

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();
        for(int i=0 ; i<parameterMappingList.size() ; i++){
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String context = parameterMapping.getContext();

            //反射
            Field declaredField = parameterTypeClass.getDeclaredField(context);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);

            preparedStatement.setObject(i+1,o);


        }
        //5.执行sql
        preparedStatement.execute();
    }

    //获取到了参数的类型
    private Class<?> getClassType(String parameterType) throws ClassNotFoundException {
        if(parameterType!=null){
            Class<?> aClass = Class.forName(parameterType);
            return  aClass;
        }else{
            return  null;
        }
    }

    /**
     * 完成对#{}的解析工作:1.将#{}使用？代替，2：解析出#{}里面的值进行存储
     */
    private  BoundSql getBoundSql(String sql){

        //标记处理类：配置标记解析器完成对占位符的解析处理工作
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{","}", parameterMappingTokenHandler);

        //解析出来的sql
        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();
        BoundSql boundSql = new BoundSql(parseSql,parameterMappings);
        return boundSql;

    }
}
